Molecular Reproduction & Development Volume 78, Issue 8 cover image

Transmission electron micrograph of a sea urchin (Strongylocentrotus purpuratus) spermatozoon (purple) bound to the tip of an egg microvillus (yellow) by the bindin protein (diffuse purple), which was released during exocytosis of the sperm acrosomal vesicle. Egg microvilli are approximately 0.25 µm in diameter. More on observing these events on the cellular level in a classroom laboratory setting is presented by VD Vacquier (this issue).